You may have to go with a commercial mortgage to achieve this arrangement (I do not know if residential lenders in the great state of Tejas will allow a 10% Vendor carry and a 15% down payment ... perhaps @Hattie Dizmond or @Bill Gulley could lend insight)A final strategy might be to lease the entire building from the owner - with the right to sublet the individual units (ye olde sandwich lease).  

If they want to change the living arrangments in the future the daughter would need to re-apply on her own.

County laws (at least in San Diego county) requires you to disclose to the owner in the written agreement all financial arrangements between the parties.

Therefore, you can't structure a an arrangement to recognize a gain on stock and attempt to offset that gain with passive activity losses from a rental property.  

Use one blanket insurance policy for each business ownership arrangement (eg - one for personal, one for anything owned by you that is for profit, one for anything owned by you and person X, another for person Y, etc).

She has shown signs of some physical, sexual or emotional abuse (we are not sure what yet) and I plan to enroll her in play therapy (per recommendations from our friend who is a preschool owner and teacher.)

The bigger guys do some hedging and have arrangements with the gas suppliers that can mitigate some risk.

If each unit does not have their own specific space I would put the patio, chairs and a table or two smaller tables Maybe an arrangement of colorful adirondike chairs (very durable). 

What are some of the normal payoff arrangements for private money lenders?

If you can't grant that as a landlord I, as a perspective resident, would probably look for a different living arrangement.